Preliminary antidiarrhoeal activity of methanolic extracts of Securinega virosa (Euphorbiaceae)

Securinega virosa is used as remedy for diarrhoea in tropical Africa, but has not been investigated for its antidiarrhoeal activity. This study was therefore aimed at investigating the methanolic extracts of the leaves, stem bark and root bark for antidirrhoeal activity, using castor oil-induced diarrhoeal model in mice. The effects of these extracts on perfused isolated rabbit jejunum were also evaluated. The methanolic leaves extract (8 x 10-5 – 1.6 x 10-3 mg
ml-1) produced a dose-dependent relaxation of the rabbit jejunum, while the methanolic stem bark and root bark extracts (2 x 10-5 – 3.2 x 10-3 mg
ml-1) produced contraction of the tissue. The methanolic root bark extract produced a dose-dependent protection against the castor oil- induced diarrhoea with the highest protection (100%), obtained at 100 mg
kg-1 comparable to that of loperamide (5 mg
kg-1), the standard agent. The leaves extract also protected the mice but was not dose-dependent. The highest protection (60%) was obtained at the lowest dose (50 mg
kg-1). The stem bark extract did not protect the animal against diarrhoea. The preliminary phytochemical analysis revealed that the three extracts contained similar phytochemical constituents which include alkaloids, tannins, saponins, flavonoids and cardiac glycosides. However, only the leaves extract contained anthraquinone glycosides. The acute toxicity test revealed the median lethal dose (LD50) values for the leaves, stem bark and root bark extracts to be 1265, 288.5 and 774.6 mg
kg-1 respectively. This suggests that the stem bark extract is relatively the most toxic. These results obtained revealed that the leaves and root bark extracts possess pharmacological activity against diarrhoea and may possibly explain the use of the plant in traditional medicine.